<!DOCTYPE html>
<html>

<head>
    <meta charset="UTF-8">
    <title>flex占比</title>
    <style type="text/css">
    .box {
        height: 300px;
        background: blue;
        display: flex;
    }

    .box div {
        width: 200px;
        height: 200px;
    }

    .box1 {
        flex: 1;
        background: red;
    }

    /*.box2 {*/
    /*    flex: 3;*/
    /*    background: orange;*/
    /*}*/

    /*.box3 {*/
    /*    flex: 2;*/
    /*    background: green;*/
    /*}*/
    </style>
</head>

<body>
    <div class="box">
        <div class="box1">flex:1</div>
        <!-- <div class="box2">flex:3</div>
        <div class="box3">flex:2</div> -->
    </div>
</body>

</html>